Meaning of auxotroph

aux•o•troph

Pronunciation: (ôk'su-trof", -trōf"), [key]
— n. Biol.
  1. a mutant organism, esp. a microorganism, that has a nutritional requirement not shared by the parent organism. Cf. prototroph (def. 1).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.